Compressor unloader



COMPRESSOR UNLOADER Filed Aug. 11, 1932 5 Sheets-Sheet 2 INVENTOR.

G02 nFMtlla Z at H15 ATTORNEY.

UNI E STATES Cir 30: and

Patented Feb. 5, 1935 PATENT OFFICE COMPRESSOR UNLOADER Gordon F. McClay, Sherbrooke, Quebec, Canada, a'ssignor to Ingersoll-Rand Company, Jersey City, N. J a corporation of New Jersey Application August 11, 1932, Serial No. 628,289

6 Claims.

operation throughout prolonged periods of time without necessitating frequent inspections or repairs. I

Other objects will be in part obvious and in part pointed'out hereinafter.

. In the drawings forming a part of this speciflcation and i n which similar reference characters refer to similar elements,

Figure 1 is; a sectional elevation illustrating an unloader constructed in accordance with the practice of the invention and showing it applied to an inlet valve mechanism of a compressor,

Figures 2 and 3 are transverse views taken through Figure l on the lines 2-2 and 3--3 looking in the direction indicated by the arrows,

Figures 4 and 5 are views similar to Figure l showing modified forms of the invention, and

Figure 6 is a transverse view taken through Figure 5 on the line- 6-6 looking in the direction indicated by the arrows.

Referring more particularly to the drawings at first to the-form of the invention illustrated in Figures 1, 2 and 3, A designates in general, a compressor unloader and a valve mechanism to which it is applied. B designates a portion of a compressor cylinder and C a head 1 therefor which forms a closure for a compression chamber D within the cylinder B and wherein is disposed a piston E for compressing the fluid medium admitted into the compression chamber D.

The form of the cylinder B illustrated comprises a pair of walls F and G which are suitably spaced with respect to each other to form therebetween a passage H through which the working substance intended to be compressed by the piston E flows to the compression chamber D.

I In the walls F and G are apertures J and K, respectively, which are in substantial alignment with each other. The aperture J affords communication between the passage H and the compression chamber D. A cover L is provided for the aperture K, and said cover may be secured to the outer wall G of the cylinder B in any well known manner. l

Thevalve mechanismselected for, the purpose of illustrating a practical application of the unloader is of the cylindrical type. It comprises an annular valve seat which seats against a shoulder P in the inner wall F of the cylinder B and has a series of longitudinally extending ports Q arranged radially in the valve seat 0 and opening at their inner ends into slots R in the inner surface of the valve seat.

Seated in the slots R, to control the ports Q, are valve plates S in the form of strips of less width than the slots R so that the fluid flowing through the ports Q may pass freely around the edges of the valve plates into the valve seat 0.

In. order to maintain the valve plates S seated over the ports Q during the compression stroke of the piston E said valve plates are provided with springs T of the curved plate type. The springs T may lie in the slots R. and seat with their ends against the valve plates. A suitable stop member U is provided for the valve plates S in the form of a cylinder disposed within the valve seat 0 and extending, in the present instance, with one end into the aperture J to hold. the valve mechanism and the associated devices in coaxial alignment therewith.

The stop member U is provided with alternately arranged longitudinally extending slots and ribs V and W respectively. In the assembled position of the stop member U the slots V lie in staggered. relationship with the ports Q and the ribs W lie in the same radial planes as the ports Q to act as seats for the curved portions of the springs T.

Disposed within the stop member U is a filler piece X for minimizing the clearance within the valve mechanism. The plug X seats upon and is supported by the stop member U which, in turn, is supported by the valve seat 0.

In accordance with the practice of the invention the filler piece X is provided with a lateral flange Y to support a casing Z having a recess 12 into which extends a boss 0 of the filler piece X for centralizing the casing Z with respect to the filler piece. On the periphery of the casing Z is a flange d which lies within the aperture K and may be in body engagement with the wall thereof.

Aclosure is provided for the outer end of the recess 13- in the form of a cover e having a pressure chamber f of which a flexible diaphragm g, clamped between the cover 6 and the casing Z, forms a-clos-ure. The cover e may be secured to the casing Z by screws h which extend through the cover e and the diaphragm g and are threaded into. the casing Z for clamping the edge of the diaphragm between the cover and the casing.

Disposed within the recess b to reciprocate upon which the diaphragm g rests. The plunger :i

is of smaller diameter than the recess b and has a recess is to receive an extension 0 on the filler piece X which guides the plunger 7. Onthe periphery of the plunger 7' are a pluraiity of radial lugs 12 which preferably extend into slots q in the casing Z and may, if desired; be in body engagement therewith to prevent relative rotary movement between the plunger 7' and the casing In the free or outer ends of the lugs p are pivots 1' upon which are mounted valve lifting elements s in the form of bell cranks of which an arm 25 extends along the valve seat 0. and lies substantially in the same radial plane as the'valve plate S which it is intended to control. The free ends it of the arms t preferably lie closely adjacent the valve plates S so that only a slight movement of the lifting devices is required to carry the ends u of the arms t into engagement with the valve plates. 1 y

In order to efiect an oscillatory movement of the lifting elements s upon movement of the plunger the other arms 12 of the lifting elements extend with their free ends 111 into an annular siot a: in the periphery of the extension 0. p The upper and lower surfaces cf the ends w" of the arms 2: may be suitably rounded to assure free oscillatory movement of the ends 112 Within the slot 33.

Preferably the lifting elements 3 are provided with flat seating surfaces y which; in the retracted position of the plunger 9' and, therefore, the lifting elements s, seat against a surface a on the flange d to retain the ends u of the arms t normally out of engagement from the valve plates S. v

Although, as may be readily appreciated, the plunger 1' is susceptible of being actuated manually forrocking the lifting elements 8 into and out of engagement with the valve plates, it is preferred to actuate the plunger in one direction by means of pressure fluid and in an/opposite direction by spring pressure. The unloader is accordingly provided with means for introducing pressure fluid into the pressure chamber f. The means employed for this purpose in the present instance comprise a bolt 2 threaded into the I cover and seating upon the cover 6 to clampthe casing Zand the elements constituting the housing of the valve mechanism'firmly in position.

In the bolt 2 is a passage 3 which registers with a passage 4 in the cover e. The pressure fluid may be supplied to the passage'B by a conduit 44 leading from a suitable source of supply, as

for instance the storage'receiver into which the compressor discharges.

Within the filler piece X and the extension 0 is an aperture 5 for the reception of a'sprin'g 6 which seats against the end wallof the recess is for actuating the plunger 7' in the direction of the cover e.

Any suitable and well known valve means (not shown) may be interposed in the conduit 44 for automatically admitting pressurefluid into the pressure chamber 7 foractuating the plunger to rock the lifting elements 3 against the valve plates whenever the receiver pressure reaches a maximum predetermined value which it maybe desired to maintain and to automatically e'xhaust such pressure fluid from the pressure chamber 7 after the receiver pressure again drops be -f low the predetermined maximum value/ During the normal operation of the compressor in the storage receiver is below the predetermined the plunger 9' will be held retracted by the spring 6 and the lifting elements s'will be retained out of engagement from the valve plates by the surfaces :1; which will then seat against the surfaces 2 of the flange d. With the parts in the positions described the medium intended to be compressed flows through the valve mechanism into the compression chamber D upon each suction stroke of the piston E and during theusubsequent compression stroke of the piston the valve plates S will be held seated over the ports Q by the, springs T.

The valve mechanism will continue to operate in the manner described until the receiver pressure reaches a predetermined maximum value and at which time the valve device in the conduit 44 will actto communicate the chamber f with Pressure fluid will then flow into the pressure chamber and, acting against the storage receiver.

the plunger 1', will actuate the plunger, the direction of the valve mechanism. 'Ihisinov'ement of the plunger will cause the lifting eleanism. No additionalcompressed fluid will then be delivered to the storage receiver until the pressure value of its contents has been again sufficiently lowered to permit such valve device,

as may be provided for controlling thesupply of pressure fluid to the pressure haust the pressure fluid from said pressure chamber. a g

After the pressure chaniberfhas been evacuated the spring 6 will return the plunger 9' to its initial position. The lifting elements 8 will then be rocked out of engagement from the valve plates which may thereafter resume their normal functions, and the lifting elements will be held out of engagement from the valve plates by their seating surfaces which the surface a of the flanged. v

The modified form of the invention illustrated in Figure 4 differs from that 'hereinbefore described principally in the form of the valvelift I ing elements and the means whereby the said elements are actuated into engagement with the vaive plates Sfor unseating said valve plates. In the present instance the lifting-devices, herein designated by 7 are pivotally connected to later ally extending lugs 8 on, the plunger 1 by pins 9 1 which are supportedby the lugs 8 and extend through the lifting end thereof. V p

In their assembled positions the lifting devices 7, which may be in the form ofrodsor bars, extend along theside of the valve seat 0 and lie in the same radial planes as the valve plates S. On the outer surface and near the free ends 10 of the lifting elements 7 are inclined or cam surfaces 11 adapted tobear'upon a correspondingly shaped surface 12 of a guide member l3disposed 'aboutJthe valvezseat O. and to which it may be secured in any well known manner as for instance by welding, as indicated.

In order to retain the lifting elements '7 out of engagement from the. valve plates S during I the time the valve plates occupy their normal operating positions the lifting elements areprovided chamber f; to exwill then bear against elements at points near one with arms l4'-adjacent the points'through which the pivot pins 9 extend,- and on the free endsof l the arms 14 are seating surfaces 15 which seat against the surface a of the flange d.

The operation of this form of the invention is as follows: Upon the admission of pressure fluid into the pressure chamber 1 the plunger :i is actuated in the direction of the valve mechanism. This movement of the plunger will cause the cam surfaces 11 of the lifting elements '7 to slide across the surfaces 12 of the guide member 13 whereby the lifting elements are rocked in the direction of the valve plates S. Upon the continued movement of the plunger the free ends of the lifting elements 7 will unseat the valve plates S to afford continuous communication between the passage H and the compressing chamber D as long as the receiver pressure remains at or approximately at the maximum predetermined value.

After the pressure within the chamber 1 has again been sufficiently reduced the spring 6 will raise the plunger 0 to its initial position wherein the seating surfaces 15 of the lugs 14 seat against the flange 2 and thereby retain the lifting elements out of engagement from the valve plates. In this position of the lifting elements the free ends u will seat against the guide member 13 to further assist in stabilizing the lifting elements during the normal operation of the valve mechanism.

In the form of the invention illustrated in Figures and 6 the filler piece X supports a hollow casing 20 to which the diaphragm g is clamped by the cover e, and in the casing 20 is a plunger 21 that supports the suspended portion of the diaphragm. The plunger 21 is of cup-shape and in the side wall thereof are notches 22 through which extend the valve lifting elements 23.

The valve lifting elements are of angular shape having a pair of arms 24 and 25. The arms 24 extend through the notches 22 and through slots 26 in the casing 20 which lie in the same longitudinal planes as the ports Q into which the free ends 27 of the arms 25 extend.

The free ends of the arms 24 extend into an annular groove 28 in an extension 29 on the filler piece X to which it is secured by a bolt 30. A plate 31 seated upon the extension 29 and secured thereto by the bolt 30 serves as a bounding surface of the groove 28. The ends of the arms 24 which lie in the groove 28 are rounded to enable the valve lifting devices to oscillate freely with respect to the extension 29 and on these ends are shoulders 32 which engage an annular flange 33 on the extension 29 to retain the lifting elements in the correct assembled positions.

As in the modifications previously described, the valve lifting elements are normally held free from the valve plates by spring pressure. In the present instance, however, the springs, designated by 34, seat directly against the lifting elements. The springs are preferably of the curved leaf type and are seated with their tips upon the filler piece X and the bowed portions of the springs bear against the lifting elements to raise said elements and the plunger 21 which they support.

I claim:

1. A compressor unloader, comprising a valve seat having a plurality of radially arranged ports, valve plates to control the ports, a fluid pressure actuated reciprocatory member, a fixed member to guide the reciprocatory member, and a plurality of radially arranged valve lifting devices pivotally connected to the reciprocatory member 'on the fixed member to cause the outer ends of the arms to rock against the valve plates to unseat said valve plates upon movement of the reciprocable member, a pressure area on the reciprocable member subjected to pressure fluid for actuating said reciprocable member in one direction, and a spring for returning the reciprocable member.

3. A compressor unloader, comprising a valve seat having a series of radially arranged ports, valve plates to control the ports, a movable member having a plurality of radially extending lugs thereon, a fixed member to guide the reciprocable member, individual bell cranks pivotally connected to the lugs and lying in the same radial planes as the valve plates, the inner end of one arm of each bell crank being fulcrumed on the fixed member to cause the outer ends of the other arms of the bell cranks to be pressed against the valve plates for unseating the valve plates upon movement of the reciprocable member, a pressure area on the reciprocable member subjected to pressure fluid for actuating the reciprocable member in one direction, and a spring for returning the reciprocable member.

4. A compressor unloader, comprising a valve seat having a port, a valve plate to control the port, a reciprocable member, a valve lifting device pivotally connected to the reciprocable member, and a guide member aflixed to the valve seat to tilt the valve lifting device against the valve plate for unseating said valve plate.

5. A compressor unloader, comprising a valve seat having a series of radially arranged ports, valve plates to control the ports, a reciprocable member, a plurality of lifting devices pivotally connected to the reciprocable member, means for causing the lifting devices to rock through radial planes against the valve plates for unseating said valve plates, a pressure area on the reciprocable member subjected to pressure fluid for actuating said member in one direction to actuate the valve lifting devices against the valve plates for unseating the valve plates, and a spring acting against the member to return said member and to maintain the lifting devices normally out of engagement from the valve plates.

6. A compressor unloader, comprising a cylindrical valve seat having a plurality of ports in its periphery, valve plates to control the ports, anchor means aflixed to the valve seat, valve lifting devices fulcrumed with one end to the anchor means and extending along the periphery of the valve seat with their other ends to points adjacent the valve plates, fluid actuated means acting directly upon intermediate portions of the valve lifting elements for rocking the said elements to unseat the valve plates, and springs acting against the lifting elements to restore said elements and the plunger to their initial positions.

GORDON F. McCLAY. 

